1. Field of the Invention
This invention relates to power supply boards for computers, and more particularly, for power supply boards with inductors which conduct heat away from the board.
2. Background Information
It is standard engineering practice to mount electromagnetic inductors on a PC board along with other heat generating electrical components. Ordinarily, the inductor is placed on the board so that heat generated within the winding of the inductor is conducted along the winding terminals to a thermally conducting path, and also the heat generating electrical devices are connected so that heat is conducted along their lead wires to a thermally conducting path. Usually the thermally conducting paths are parallel to the plane of the PC board, and ultimately a heat sink is thermally connected to the heat conducting path. Also, airflow across the heat generating electrical components helps to re move heat which they generate.
When high power heat generating electrical components are attached to one side of a PC board, often it is necessary to couple a heat sink to the planar surface of the other side of the PC board in order to conduct the heat which they generate away from the components, so that the heat can be transferred to airflow by the heat sink. Then, when logic circuit elements are needed in the design, the logic circuit elements must be mounted on a second PC board. The two PC boards must then be connected by numerous electrically conducting wires, or posts, leading to a complicated mechanical structure which is expensive to manufacture.
There is needed a simplified method of conducting heat from high power heat generating electrical devices, and also there is needed a method of mounting inductors and logic circuit elements on an assembly of PC boards and heat sinks.
An inductor is arranged so that the metallic winding is used to conduct electricity around the circular path of the winding, and also is used to conduct heat from a first side of the winding, through the metallic structure of the winding, to a second side of the winding. The heat received by the metallic material of the winding at the first side is conducted along the metallic structure of the winding to a heat sink on the second side of the winding. The inductor is mounted on a PC board having high power heat generating electrical devices which generate heat also mounted on the PC board, and the heat generated by the heat generating electrical devices is conducted by the metallic material of the inductor winding to a heat sink mounted in thermal contact with the winding, and mounted substantially parallel to the plane of the PC board.
In an exemplary embodiment of the invention, the inductor has one turn. The winding is formed in the shape of a hollow, slotted cylinder with the slot substantially parallel to the axis of the cylinder, the slot forming the two electrical ends of the winding. The ends have a flattened surface to improve their contact with the planar pc board surface, and are connected electrically to a circuit by soldering the respective flattened surfaces to a copper layer of the PC board. The winding also has a flattened surface opposite the slot, and this flattened surface is thermally connected to a heat sink. Heat generated by the heat generating electrical devices is conducted through the copper layer to the winding, and is conducted through the winding to the heat sink. In a further exemplary embodiment of the invention, the heat generating electrical devices are mounted on a first side of the PC board, heat is conducted from these devices through the board by thermally conducting vias which are filled with solder to a second side of the PC board, the inductor is mounted on the second side of the PC board, the heat is conducted to the winding by the vias and copper layers of the PC board which is electrically connected to the ends of the winding. The winding then conducts the heat away from the pc board to the heat sink which is thermally attached to the winding at the flattened surface opposite to the electrical ends of the winding.
Use of the inductor winding as a thermally conducting path simplifies the assembly, and allows the components of a power supply module, namely the PC board, high power heat generating electrical components, inductor, and heat sink, to be formed into a compact unit which is easier and cheaper to manufacture than previous designs.